MTD Yardman Pulley Removal.

[hs5424]

Hi All,
I have removed the engine from my MTD Yardman mower to check the piston rings as I noticed a large "blow back" pressure ( my own term ) when I remove the oil dipstick when in use last summer. I also checked the compression when cold and remember it reading 55psi and 90 ish when warm. I need to remove the main pulley which is on the crankshaft. I don't want to try a standard wheel pullers as the 2 pulley wheels look as if they could be damaged if I put them under pressure with the pullers. I am considering welding a large nut to the bottom of the pulley and screwing a large bolt up into the pulley shaft which should pull the pulley off the main shaft.
Yardman model 136C561C643
Engine Briggs and Stratton 11.5hp IC engine.
Yardman machines are rare here in Ireland so I cannot ask any questions locally. It has proven to be a good little piece of kit for over the past 20 years and will keep it running as long as I can.
Any hints or advise appreciated.

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[ILENGINE]

Heat and penetrating oil will be your friends. Since the engine is off the mower, which is lucky since most don't come off with the pulley attached. You can also hang the engine from the pulley and let gravity assist you in removal. Just make sure to have something that the engine can land on if the pulley slides off.

 

[bertsmobile1]

If you can get something between the sump and the pulley that bears against the boss and not the edge of the pulley like some tyre irons or wrecking bars.
Flip the engine upside down and put a cap screw into the end of the crankshaft to protect it.
Then with an air hammer lay into the end of the cap screw.
With the weight of the engine plus the 1,000 little whacks a minute it will usually shock the pulley off. very slowly .
A bit of heat will not hurs as will some of your favourite penetrant poured down the key slot.
Some I have done here have taken the best part of a full day to do but they all come off in the end.
The important thing is to only press on the boss part of the pulley and of the flange part of the pulley.

 

[Hammermechanicman]

With bert on the air hammer. I have crank bolts i have drilled a 1/4" wide by 1/4" deep divots in to use with the air hammer. You won't be able to hold the point of the air hammer bit on the flat head of the bolt. If you try it drill a divot in the head of the bolt.

 

[hs5424]

I setup a flat piece of cast iron ( not ideal material ) with a slot cut out of it that fitted snugly around the main shaft . I welded two vertical pillars on the flat cast iron that I placed into the cross arm of a hydraulic pullers. Putting pressure on the pullers lifted the iron plate up against the pulley tube but alas the 3/8'' cast iron plate snapped in half. No sign of any movement at all. I may have to take to machine shop and see if they can remove it.

 

[hs5424]

UPDATE.,
I had to make an attachment to fit tight to the crankshaft and put pressure against the pulley shoulder using an hydraulic pullers. Severe pressure was required to remove the pulley. I now have the piston and rings removed and I am going to order a new set of rings, wheather the originals are worn or not. Everything looks very clean inside the crank case and the piston appears to have no side movement when in the barrel. Theres no sign of scoring or wear in the cylinder barrel . Does anyone know if I insert one of the rings into the cylinder what gap should I expect between the ring ends. I know I would probably need a new ring to insert first and make comparsons. Also, when putting all back together again what type of gasket do you suggest for the crank case.
See pulley removal setup.

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[bertsmobile1]

Congratulations .
Buy the gasket rebuild kit most will have multiple sump gaskets which are used to set the end float on the crank .
Measure the depth that the sump oil seal is set to and write it down as too deep will cause oil flow problems
When you replace the pulley use liberal amounts of nickel anti sieze on the shaft ,'
Fill the key way, push the pulley back up then push some more up the key way and next time it will drop off into your hands.
All bar one of these I have done had the belt keepers bent back because the owners could not pull the pulley down far enough to replace the drive belt.
To give you ring gaps we will need the full engine numbers that are stamped into the rocker cover

 

[hs5424]

Thanks B,
I ordered a piston and rings and a cylinder head gasket this afternoon. I reckon that as I have the engine removed and stripped, the extra cost for a piston is well worth it. I intend using a chemical gasket on the sump casing. I cleaned the crank shaft that held the pulley with some fine paper and oil and it now pops on by hand. One thing I noted before I removed the cam gear is when both timing marks are aligned ie, crank shaft and cam gear, the piston is not TDC. Just an observation. I now have to sit and wait for the spares to arrive.
Will keep all updated.

 

[bertsmobile1]

Silicon on the sump is a no no no .
IT will clamp the crankshaft too tightly.
Note there is no thrust washer or bearing on the bottom of the crank, it just sits there on the sump.
Some rebuild kits have 3 gaskets of different thicknesses while other will have 3 thin ones to be sacked .

 

[hs5424]

Thanks for that. I will see if I can get one. If I realized this earlier I would have ordered one when I placed order for the piston.